The present invention relates to a device and a method for face alignment. More particularly, the present invention relates to a device and a method for face alignment used for adjusting faces and center axes of optical components upon bonding the optical components.
In order to adjust faces and center axes of optical components upon bonding them, a face tracing/center axes aligning mechanism as shown in FIG. 6 is conventionally employed.
This mechanism is provided with a stacked adjustment stage unit which is attached with a clamp member 121. The clamp member 121 clamps one object 120. The stage unit includes a height adjustment stage 122, a transversal adjustment stage 123 and a longitudinal adjustment stage 124. The mechanism is further provided with a height adjustment stage 114, a transversal adjustment stage 115, a longitudinal adjustment stage 116, a longitudinal flap stage 117, a transversal flap stage 125 and a clamp member 118 for clamping the other object 119.
In the above-described structure, the objects 119 and 120 are set and clamped by the clamp members 118 and 121, respectively. Here, the center axes of the objects 119 and 120 are matched by adjusting each of the stages as confirmed by the outer appearance or optical transfer characteristic of the objects.
Then, after the object 120 is lowered by the height adjustment stage 122 and the state of face contact between the objects 119 and 120 is confirmed, face alignment takes place. Specifically, after confirming face contact between the objects 119 and 120, the objects are once separated from each other to adjust the transversal flap stage 125 and the longitudinal flap stage 117 so as to find positions where the faces of the objects are parallel to each other. At this point, positions of the center axes of the objects 119 and 120 are once again confirmed. In most cases, the center axes are offset from each other at this point, and thus the above-described adjustment is repeated for several times to align the center axes and the faces of the objects 119 and 120.
Another example of a conventional face alignment device is disclosed, for example, in Japanese Patent Laid-Open Application No. 8-281464, which is shown in FIG. 7.
This face alignment device is provided with a clamp member 107 for securing one object 108 on a seat 106 which has a convex spherical surface on one side. In this device, the other object 109 is lowered perpendicularly onto the object 108 so as to allow contact between the faces of the objects. Specifically, in order to allow contact between the faces of the objects, the seat 106 having the convex spherical surface is slidably accommodated in a seat support member 103 which has a concave spherical surface formed in a base block 101. An air compressor pump 113 sends air via a switch valve 112, an air guiding path 111, an air receiver 102 and air throughholes 104 that are formed through the seat support member 103, thereby forming an air layer 105.
The air layer 105 formed as described above will cause the seat 106 having the convex spherical surface to float, thereby eliminating sliding resistance between the seat 106 and the seat support member 103. Then, the object 109 is lowered perpendicularly onto the object 108 so that faces of both objects make contact with each other. At this point, the seat 106 having the convex spherical surface freely slides so that the face of the object 108 traces the tilt of the contacting face of the object 109.
Accordingly, the faces of the objects 108 and 109 can be aligned by applying pressure to each other. Thereafter, the injected air is evacuated by a vacuum pump 114 via the switch valve 112, whereby the seat 106 is suctioned and makes contact with the seat support member 103. Since no pressure applying mechanism such as the above-mentioned air compressor pump is placed near the contact faces of the objects on the seat 106, laser light sources 110 can be provided at any positions substantially horizontal to the objects, thereby enabling to weld the objects 108 and 109 together.
As a third conventional example, Japanese Patent Laid-Open Application No. 7-63961 discloses a method for assembling an optical semiconductor module. This method uses a jig having first and second blocks. The first block has an upper surface with a setting hole for holding a lens holder member having an optical semiconductor device, and a convex semi-spherical bottom surface. The second block has a concave semi-spherical surface corresponding to the convex semi-spherical surface of the first block so as to rotatably hold the first block. This jig secures an optical fiber and the lens holder member held in the setting hole of the first block while they are making contact. Thus, the center axes of the lens holder and the optical fiber can easily be adjusted upon assembly, while their faces are maintained to be parallel to each other, thereby enhancing optical accuracy.
However, in the face tracing/center axes adjusting mechanism according to the first conventional example, each object is adjusted by the mechanism of triaxial or pentaxial stages. As a result, the size of a control system becomes considerably large as compared to the size of the product, and a large area of the work area will be occupied by the device. In addition, since there are many axes involved that need to be controlled, operation of the device takes a long period of time, thereby deteriorating the working efficiency.
In the face alignment device and the method for assembling an optical semiconductor module according to the second and third conventional examples, respectively, the objects are placed on a flat surface opposite to the convex spherical surface, in the vicinity of the center axis of the convex spherical surface. Accordingly, external force is mostly applied downward, and thus force for letting the face of the object to trace the tilt of the other face (i.e., force for promoting rotation along the spherical surface) becomes small. Thus, in order to promote rotation of the spherical surface with the load applied to the center axis of the upper surface to let one face trace the other, a considerably large force is required, which may result in breaking or damaging the objects.
As another problem caused in the second and third conventional examples, objects are not placed at a position corresponding to the center of the spherical surface, which may result in offset of center axes of the objects from each other. If the objects are placed at a position corresponding to the center of the spherical surface, the faces can trace each other without changing the center axes of the objects and using the center axis as a base point. However, in the conventional examples, objects are not placed at a position corresponding to the center of the spherical surface and thus the center axes of the objects are offset from each other. As a result, the center axis needs to be readjusted after face tracing.
In more detail, as a general procedure, faces of the objects are allowed to make contact with each other such that there is no space between them, and then, the center axes of the objects are aligned. However, face tracing followed by alignment of the center axes of the objects needs to be carried out for several times while confirming the appearance or the optical transfer characteristic of the objects, thus requiring a long period of time.
In the face alignment device of the second conventional example, in order to eliminate sliding resistance between the seat support member and the seat clamping the object, the convex spherical surface of the seat is floated by forming a layer with air injected through the air throughholes in the concave spherical seat support member. The thickness of the air layer formed between the seat and the seat support member is several xcexcm.
In the following step, face of one object is allowed to trace the face of the other object and the position is determined. Then, the air sent during the alignment and position determination is evacuated by the vacuum pump by switching the switch valve, whereby the convex spherical surface of the seat is suctioned and attached to the concave surface of the seat support member. Since this causes a gap between the objects and changes the load applied on the upper surface, a mechanism for following the change of the load is further required. In addition, the gap also causes change in the optical transfer characteristic.
In view of the above-described problems in conventional face alignment devices and the like, the present invention has an objective of providing a device and a method for face alignment that can be realized with high accuracy, a simple structure, a short period of time for adjustment, high productivity, and without causing breakage or damage of the objects.
In order to achieve the above-described objective, a face alignment device according to the present invention comprises two units that are each provided with: a convex semi-spherical block having a contact surface that makes contact with a clamp member for securing an object and a convex semi-spherical surface on the opposite side of the contact surface; and a base block having a concave portion corresponding to the semi-spherical surface of the convex semi-spherical block for rotatably holding the convex semi-spherical block. The two units are arranged such that their contact surfaces face each other.
According to the present invention, the convex semi-spherical blocks securing the objects are rotatably held in the concave portions of the respective base blocks. Accordingly, when a load is put on one object secured on the convex semi-spherical block via the other object to be bonded with, the objects are free to move so that face matching can be realized without causing a space between the objects. Since each unit has a simple structure of the convex semi-spherical block and the base block, they can be controlled easily.
A face alignment device according to the present invention further comprises an air layer forming means for forming an air layer between each of the semi-spherical surfaces of the convex semi-spherical blocks and each of the concave portions of the base blocks; and a moving means for moving the two base blocks to be close to or apart from each other.
According to the present invention, while the objects secured perpendicular to the convex semi-spherical blocks are subjected to face matching, face alignment and bonding, an air layer is formed between each of the convex semi-spherical blocks and each of the concave portions of the base blocks. When the air layers are evacuated thereafter such that the convex semi-spherical blocks make contact with the respective concave portions, the objects may move in the gap taking place of the air layers, which may cause a space between the objects. However, according to the present invention, the air layers are eliminated while the two base blocks (i.e., the concave portions) are translated toward each other. Thus, the objects can be bonded accurately without moving.
In a face alignment device according to the present invention, the clamp member is provided with a bearing so that it can rotatably hold the object.
According to the present invention, since the objects are rotatably held by the bearings, not only the faces of the objects (e.g., optical components) but the optical center axes of them can also be aligned. Thus, face alignment can take place with respect to the best position for optical transfer characteristics of the optical components.
Furthermore, in a face alignment device according to the present invention, the object is held outside the two units by the clamp member, while a weight is provided at the other end of the clamp member opposite to the object.
According to the present invention, the clamp members can hold the objects outside the two units. As a result, the objects are uncovered, which allows efficient operations such as adhesion application and laser irradiation. In addition, since a weight is provided at the other end of the clamp member opposite to the object, the convex semi-spherical blocks will not be displaced by the load put upon face matching and face alignment of the objects, thereby allowing operations in a stable manner.
In another aspect, the present invention is a face alignment method, comprising: arranging two units, which are each provided with a convex semi-spherical block having a contact surface that makes contact with a clamp member for securing an object and a convex semi-spherical surface on the opposite side of the contact surface, and a base block having a concave portion corresponding to the semi-spherical surface of the convex semi-spherical block for rotatably holding the convex semi-spherical block, such that the contact surfaces of the two units face each other; and securing one of the objects with the clamp member. The clamp member is arranged on the contact surfaces of the two units at eccentric positions from the center axes of the contact surfaces.
According to the present invention, the clamp member is held at an eccentric position from the center axes of the convex semi-spherical blocks. Accordingly, the load for allowing rotational sliding between each of the semi-spherical surfaces of the convex semi-spherical blocks and each of the concave portions of the base blocks can be small. For example, the load can be as small as several-tens of grams which has conventionally been from several-hundreds of grams to several kilograms, thereby preventing breakage and damage of the objects as well as rendering control of the load easy. No space is caused between the faces of the objects, which results in enhancement of performance and thus enhancement of productivity.
In a yet another aspect, the present invention is a face alignment method, comprising: arranging two units, which are each provided with a convex semi-spherical block having a contact surface that makes contact with a clamp member for securing an object and a convex semi-spherical surface on the opposite side of the contact surface, and a base block having a concave portion corresponding to the semi-spherical surface of the convex semi-spherical block for rotatably holding the convex semi-spherical block, such that the contact surfaces of the two units face each other; and securing one of the objects with the clamp member. The faces of the objects are aligned while the clamp member is arranged on the contact surfaces of the units such that the center point of the face of one of the objects corresponds to a center point of an imaginary sphere formed by the facing semi-spherical surfaces of the convex semi-spherical blocks.
According to the present invention, the faces of the objects are aligned while the center point of the face of one object is matched with the center point of the imaginary sphere. Therefore, face alignment can be performed easily without the center axes of the objects being offset from each other.